The present invention relates to a construction machine with an electric generator and having a hydraulic oil system adapted for cooling the generator. The construction machine can be, for example, a road paver or a feeder for a road paver.
From EP 1 118 714 A2 it is known that there are electric devices with high electric power consumption levels in the road paver. These include, for example, the heating devices and heating rods of the screed for heating the asphalt mixture. In order to supply power to these devices, a powerful electric generator is needed that normally is coupled to and driven by an auxiliary electric drive, for example by a pump transfer gear. The auxiliary drive is driven by a primary drive, for example by a diesel motor. Due to the high level of electric output during operation, such a generator generates a high level of heat of its own, for which reason cooling air is supplied to the generator by means of a fan. Disadvantageous in this is that the fan demands a certain constructed space on the generator and within the construction machine, and the cooling capacity is limited.
It is also known that in motor vehicles and commercial vehicles, another type of electric generator, referred to as a dynamo, is used to generate the vehicle electrical system voltage. Additionally known is that these electric generators are also subjected to different heat sources during operation or that they themselves generate heat, for which reason they have to be intermittently or continuously cooled. On the one hand, the generator is for the most part located close to a combustion engine, on the other hand, it generates a certain heat of its own during operation. In motor vehicles, air cooling of the generator can be sufficient, while liquid cooling is advisable in vehicles with a higher vehicle electrical system voltage. A liquid-cooled generator is known, for example, from DE 30 28 177 C2, in which a generator with a rotor winding with cooling channels in the conductors is described. The cooling channels can be perfused with cooling water.
A further liquid-cooled generator is described in DE 198 54 464 C2. The generator is located in a housing that comprises a ring-shaped gap for cooling fluid.
Disadvantageous in the cited state of the art is that for the most part, electrically conductive water is used in close proximity to electric components.
Known from DE 197 50 379 B4 is a construction unit with an electric generator and a hydraulic pump assembly in which the hydraulic pump assembly is provided to cool the generator. Disadvantageous in this case is that the generator and the pump assembly form a common construction unit and can therefore be separated spatially only with difficulty.
The object of the present invention is therefore to ensure better cooling of an electric generator with the simplest possible means.